Electrical heating element for pressure cookers



Jan. 2, 1923. 1,440,826.

E. G. HAGER. ELECTRICAL HEATING ELEMENT FOR PRESSURE COOKERS. FILED1'uLY5,1s21.

2 SHEETS-SHEET l.

Jan. 2, 1923. 1,440,826. E. G. HAGER. ELECTRICAL HEATING'ELEMENT FORPRESSURE CYOOKERS.

FILED JULY 5, I92].

2 SHEETSSHEET 2.

Patented Jan. 2, 1923.

iUNITED STATES PATENT OFFICE.

nvnanr'r e. HAGER, or KIMBERLY, IDAHO, Assmnon or ONE-HALF To s'runn'rB.

ROUGH, or TWIN FALLS, IDAHO.-

ELECTRICAL HEATING ELEMENT FOR PRESSURE COOKERS.

Application filed July 5,

To aZZ whom it may concern Be it known that 1 Evnnn'rr G. Hears, acitizen of the United States, residing at Kimberly, county or TwinFalls, and State oi? Idaho, have invented certain new and usefulImprovements in Electrical Heating Elements for Pressure Cookers; and 1do declar e the following to be a full, clear, and exact description. orthe invention, such as will enable others skilled in the art to which itappertains to make and use the same, reterence being had to theaccompanying drawings, and to the characters of referencemarked thereon,which .torm a part or this specification.

-" lh's invention relates to pressure cookers and has special referenceto that type of cooker that employs an electric heater ele ment for thegeneration or the heat required for its operation.

It has been found by experiment that where an electric heater element isused some special provisions must be made to prevent it from becomingtoo hot and burning out in case the cooker becomes dry: this usuallyoccurs where the heater element is attached to the bottom by materialwhich is not a good heat conductor and where the heating element isimmersed in the liquid.

it is the object of this invention to so relate the heater element tothe device to which it is attached that there will be a good heatconducting path from both sides of the heating element to the liquid orother object to .be heated. It is also my object to so design and relatethe parts that there will be a uniform distribution of heat over theentire surface of the heater, or in this case over the entire bottom ofthe cooker. It is also my object to provide means whereby the quantityof heat generated per unit of time may be varied to suit the conditionsunder which the cooker is operated, in this manner heat "may begenerated at a high rate until the proper temperature and pressure areattained and thereafter the rate may be made smaller, thus enabling thedevice to be operated ata high thermal efficiency.

In order to more clearly describe my device reference will be had to theaccompany- 7 ing drawing in which-- Fig. 1 is a side elevation ofmyimproved pressure cooker with parts'broken away to show the locationof my heating element.

1921. Serial No. 482,294.

Fig. 2 is a fragmentary sectional view showing the methodof joining theheat coils view with parts Figs. 7, 8 and 9 are diagrams of connectionsshowing the various combinations that can be madewith the. heatingelements.

The same reference characters indicate the same parts throughout thevarious views.

In lli 1 l have shown a pressure cooker comprising the body part 1 andthe cover 2. The cover is provided with a downwardly extending taperinggfiange 3 and outwardly projecting lugs 4: in which are notches 5 forthe reception of a clamping bolt 6 having a butterfly nut 7. The bodyportion has a plurality of sets of outwardly extending spaced lugs 8 towhich bolts 6 are pivotally attached by means of a rivet 9. The cover isfirmly clamped to the container by means of the bolt 6 and butterfly!nuts 7' whereby the tapering flange forms a steam tight fit. The coveris provided with the usual pressure gage 10 and safety valve 11. Thecontainer and cover maybe of any conventional design as it forms no partof my invention except in so far as l have modified the bottom of thecontainer so as to adapt it for-the reception of my heating element.

'- The bottom 12 of the container 1 is pro- 'vided with an annularchannel 13 to which is applied an annular cover 14 which is held inplace by countersunk screws 15 as clearly shown on the drawings. v

Within the annular space thus provided in the bottom of the container Iplace my heating'element which consists of a flat ring 16 of mica onwhich is wound two separate ance element is spaced from the edges ofchannel 13, being somewhat narrower than said channel, and is held inplace by dowel pins 19 engaging in holes 20. The depth of channel 13 isso proportioned with respect to the thickness of the heating element 16and the insulationplates l7 and 18 that the latter are held firmly inplace between the bottom of the groove and the cover i l but aresubjected to no considerable degree of pressure. Tt will be noted thatcover 14- is clamped directly against shoulders 21 and 22 by means ofthe screws 15 above referred to. This construction results in asubstantial structure and provides a good heat con ducting path fromring 14; to the body of the container; this is of great importance as itprevents thelower side of the heating element from becoming over heatedand also helps to distribute the heat evenly over the bottom or thecontainer. Extensive tests have shown that when the heating elementisenclosed in the manner described above all it will not burn outevenwhen the container is dry and water w ll boil equally well on everypart of the bottom of the container distinguished from containers whichare not provided with the embedded heating elemerit, in these latter theboiling will usually be more violent directly above the heating element.

Electrical connection to the heating element is made as indicated inFigs. 2 and 3. A. notch 23 extends from channel 13 to the outside of thecontainer. The annular cover ring llis provided with a projection 2awhich serves to cover this notch in the manner shown in Fig. 2.

Secured to the outside of the container and held in place'thereon bymeans of screws 25 is a cup-like structure 26 having a downwardlyprojecting portion which comprises two parts 27 which are locatedagainst the sides of the container and which are joined by an outwardlycurved centralportion 28 which cooperates with the extending portion 24:of ring 14 to form a closed channel for leads 29, 30 and 31 from heatcoils 4:0 and a l to contact terminals 32, 33 and 34 respectively; theseterminals are insulated from the cup-shaped structure 26 by means ofinsulating washers 35, as shown in Fig. 3. Attention is called to thefact that 29 is a common lead from the corresponding ends or both or theheating coils connecting them with terminal 32; The other ends of thecoils being each connected to one of terminals 33 and 3% by conductors30 and 31. The current is supplied from wires 36 and 37 throu h a plug38 having three socket contacts M and T spaced equidistantly so thatthey will engage with terminals 32, 33

. and 34.- in any one of the three possible positions. Sockets L and Mare connected by ajumper 39.-

Tt we make connections in the manner inraraeae degrees of heat andpermits the device to be used economically.

Although T have shown my heater enibodied in the structure of a pressurecoolrer T desire to point out that T consider that my invention isbroader than this and that the principle employed can be utilized in theconstruction of heating elements for other purposes. a

By having the heating element'enclosed in a channel provided with aremovable cover, it can be readily renewed and replaced in case it burnsout or deteriorates for any'other reason. l fe therefore get theadvantages of a cast in element with the additional advantage of havingthe heater element readily renewable.

T-Taving described my device, what T (3011"- sider 'as, my invention ordiscover and what T desire to claim is:

1. An electric heater comprising a plate of metal having a shallowchannel therein, a fiat heating element in said channel, a removablemetal cover for said channel, said cover being slightly wider thanthechannel and adapted to be clamped firmly against the heating element,and means for conducting electricity to said heating element. I

2. An electric heater comprising a metal plate having a shallow annularchannel in one side thereof, ring shaped flat heating elements in saidchannel, a cover for said channel comprising an annular member whosewidth is greater than that of said channel and means for securing saidcover to said metal plate and for clamping it; firmly against theheating element, whereby a good heat conducting path is provided betweensaid cover and said plate.

' 3. Th combination, a vessel adapted to contain a liquid, a shallowannular channel in the bottom of said vessel, an annular -1 flat heatingelement in said channel, an, annular cover for said channel, said coverbeing wider than the channel, means for attaching said cover firmly tothe bottom of said vessel and means for conducting ourrent to saidheating element.

-l.-Tn combination, a vessel adapted to contain a liquid, an annularchannel in the bottom of said vessel, a rabbet around each side of saidchannel, an annular heating element in said channel, insulating materialon each side of the heating element, a cover over said channel, saidcover fitting in said rabbets, means for securing said cover to thebottom of said vessel and means for conducting current to said heatingelement. from said annular channel to the outside 5. A pressure cookercomprising in comof said vessel, a projection on said cover e-x- 10bination a vessel having an annular channel tending over said secondchannel and conin the bottom thereof, a rahbet extending nection meanssecured to said vessel and around said channel on each side thereof,covering the last named channel.

a resistance element in said channel, a cover In testimony whereof Iaffix my signature. for said channel, said cover fitting within 7 saidrabbets, another channel extending EVERETT G.-HAGER. 1

